Current photovoltaic-based systems are expensive to produce and take from one to twenty years to recoup the amount of power required for their own production. Energy storage for photovoltaic systems must be done as electrical energy storage, which is far more costly and environmentally problematic than thermal energy storage. Various other solar thermal energy converting apparatuses are gaining support as an improvement for application to solar energy conversion. One challenge associated with all solar thermal energy-based systems is the storage and efficient transfer of thermal energy. Thermal energy storage (TES) units are an area of active research to solve this problem. Unfortunately, they are typically inefficient due to various heat transfer limitations and interfaces and often use liquid phase storage rather than phase change storage. Accordingly, a need exists for improved thermal energy storage and transfer methods, apparatus and systems.